New test results on two popular sports supplements have again found an amphetamine-like compound that's not disclosed on their labels and puts athletes at risk of being banned from competition, according to an article published Monday in the Journal of Analytical Toxicology.

The peer-reviewed article describes finding the compound in samples of the pre-workout powder Craze, sold by Driven Sports, and the fat-burning pills Detonate, sold by Gaspari Nutrition. The tests are the latest to raise questions about what's really in the two products.

The tests found that samples from four of five lots of Craze contained the compound N-ethyl-alpha-ethyl-phenethylamine, or "ETH" for short. Both Detonate samples tested positive for ETH, the study said.

The study's lead author, Mahmoud ElSohly, president of ElSohly Laboratories in Oxford, Miss., and a research professor at the University of Mississippi's National Center for Natural Products Research, was not immediately available for comment.

Marc Ullman, an attorney for Driven Sports, said the company hasn't had time to review the new journal article in depth, but a cursory review indicates it is flawed and missing key information.

"The wide variances in test results reported would seem to suggest that whatever ElSohly was seeing, it was naturally occurring," Ullman said in an e-mail. The labels on Craze and Detonate say their key active ingredient comes from dendrobium orchids.

Labs hired by Driven Sports have not found the amphetamine-like compounds in Craze, the company's officials have said. Ullman said Monday the company is in the process of having test results from its lab prepared for submission to a peer-reviewed publication, but he didn't have an estimated time frame.

Officials at Gaspari Nutrition did not immediately respond to interview requests.

The study published Monday discloses it was funded in part by Thermolife International, another supplement company.

Other groups of scientists that have found troubling compounds in Craze — including the U.S. Anti-Doping Agency in June 2012 and a government-affiliated forensic lab in Sweden in April — had no affiliation with industry competitors.

In August a team of researchers from the National Forensic Service in South Korea and the National Institute for Public Health and the Environment in the Netherlands published an article in a journal of the Japanese Association of Toxicology saying they had found a methamphetamine-like compound in samples of Candy Grape flavor and Berry Lemonade flavor Craze.

In October a team that included a researcher from the Netherlands along with U.S. scientists from Harvard and NSF International in Ann Arbor, Mich., reported in the scientific journal Drug Testing and Analysis that they also had found a chemical similar to methamphetamine — N,alpha-diethylphenylethylamine — in samples of Craze. NSF International, an organization that does testing of supplements, reported in October that separate tests of Detonate also found the same compound. Pieter Cohen, an assistant professor at Harvard Medical School and co-author of the October article, said the compound his team found in the fall is the same molecule ElSohly's team reported on in Monday's journal article, even though they used a different name to describe it.

"The important new study further confirms that Craze is not what it appears to be," Cohen said. "Far from a natural supplement, the new research confirms what we found in October: Craze contains a new stimulant never tested in humans."

Cohen said the new peer-reviewed results on Gaspari's Detonate product raise larger concerns about the integrity of products sold to consumers as supplements.

"Taken together, this research strongly suggests that we are not dealing with one rogue player, but rather an industry-wide problem in which new synthetic stimulants are introduced as supposedly natural products without consideration of the safety of consumers," Cohen said.

Despite the repeated test findings, regulators at the U.S. Food and Drug Administration have taken no public action involving Craze, Detonate or the products' makers. The agency has declined to comment on the companies and products.

In the wake of USA TODAY's investigative reports about Craze and Cahill, Wal-Mart and other large online retailers stopped selling the product, and Driven Sports and Gaspari Nutrition ceased production of Craze and Detonate.